Quantity = Quality

Scott Dikkers (founder of The Onion) wrote that the best ideas in the writers' room tended to come from generating the most ideas. The average quality of the ideas didn't matter, it was all about generating more and more ideas in general.

That's backed up by some fascinating research (summarized by Marc Andreessen here) that found ultra-successful people tended to produce their best work during the periods in which they produced their most work.

"The periods of Beethoven's career that had the most hits also had the most misses -- works that you never hear."